Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define REP(i,n) for (int i=0;i<(n);i++)
const int INF = 1e9;
using namespace std;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int dist[100][100];
int ans;
int main(){
	int H, W;
	cin >> H >> W;
	vector<string> s(H);
	REP(i,H){
		cin >> s[i];
		REP(j,W){
			if(s[i][j] == '#') ans++;
		}
	}
	queue<pair<int, int> > que;
	que.push({0, 0});
	dist[0][0] = 1;
	while(not que.empty()){
		int y, x;
		tie(y, x) = que.front();
		que.pop();
		REP(d,4){
			int nx = x + dx[d];
			int ny = y + dy[d];
			if(nx < 0 or nx >= W or ny < 0 or ny >= H) continue;
			if(dist[ny][nx] or s[ny][nx] == '#') continue;
			dist[ny][nx] = dist[y][x] + 1;
			que.push({ny, nx});
		}
	}
	if(dist[H-1][W-1] == 0) cout << -1 << endl;
	else cout << H*W - ans - dist[H-1][W-1] << endl;
	return 0;
}